For the smaller ones, you don't need jetpack, but for the mk3 hammers you will want your distance! Let them take care of the rest of the army fighting you, then pick them off with a bow or charge them with your flaming jetpack sword. If the hammer bot has a jetpack, kick it after dodging it's charge and follow up with your bow.

For sword robots (mk1 and mk2)

For mk1 and mk2 sword robots you don't have to worry much. All sword robots from mk2+ can knock your blade aside, so try not to do a front strike when there's a horde. Use your sword when there's only a few enemies, but when there's more use your hammer's side strike.

For hybrids:

Do not use your bow unless the enemy is on the ground, especially if it's a fire enemy. You can try using a bow at long range, but their dodging skill is insane and if you get close their sword will send your flaming arrow back at you. Use your sword to block their arrows until you get close, then use your hammer while walking backwards to hit them once they draw out their sword.

For mk3 sword robots:

I mostly mess around with these enemies. They jump a lot, making me cut off their feet more often than not. As with the hybrids, do not use your bow unless they are on the ground or you want to have an "Arrow duel". Keep your sword equipped, as enemy fire will likely hit them and bounce back a you. Back up when they hit, then go for the kill. If you need it gotten rid of quickly or there are a lot of them, use your hammer. It will knock them away if they're too close (Hilt smash) and will kill those at range.

For archers:

All archers are a threat without arrow block. If you have it, they do love to pull off insane trick shots in which they shoot off both of your hands, completely ignoring your block. Never look away from them unless there's a bigger threat on the board (Kick bots near lava, mk3 hammer bots, any thing on the fire island map). Keep your sword out when facing these enemies.

For kick bots:

This heavily depends on the map and where you are on it. If it's the fire island, kill them first. If there are no traps, leave them. They are why the second tree I train is the kick one.

for spider tron 5000/6000:

These enemies are not much of a threat if you're still standing and/or at a distance. Spider tron 6000 is best taken out with a bow, aim for the red eyes on both. Train your defense talents before you reach level 10, because if you don't, killing spider tron 6000 with a sword or hammer is near impossible.